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AJvYcCUTtNkXNsK8BkTtARgZhI/TDZyN7itAfBO4Zgl7jVUiIN3MFl1aPLRqcBU4QqP/YcHFA7Om11UKYbhMlTE=@vger.kernel.org X-Gm-Message-State: AOJu0YzkD4wmLNfQdwcl/EYVe6zmvIO9cmN4gUsCRsfR+1AboeM1QnzS +ZqENGt2PYyeqZujV4NTHQUI6XVT5hWrZzajEbJno8WMrCwcnWbem4HQIBcocHQI2cnA7yhb4VV SQLobwhiBzpIBhN79OJT3BMehJNICwRp9iJsS9wobuxWKmxs/mOSGlCpRFKI= X-Google-Smtp-Source: AGHT+IGYASKP8hU31QI0trilywDw31OIxZOXXBUT5ZKD8CVkHRLF0C+8oJSCZ8wIM1De8sDbw67hl19Hri2UeJckvuAe6Kdc9wql Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6e02:1c0c:b0:430:c38f:fb82 with SMTP id e9e14a558f8ab-430c5223b84mr401619015ab.8.1761429270642; Sat, 25 Oct 2025 14:54:30 -0700 (PDT) Date: Sat, 25 Oct 2025 14:54:30 -0700 In-Reply-To: <68f4abbe.050a0220.1186a4.052a.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <68fd4716.050a0220.346f24.039a.GAE@google.com> Subject: Re: [syzbot] [ocfs2?] divide error in ocfs2_block_group_fill (3) From: syzbot To: jlbec@evilplan.org, joseph.qi@linux.alibaba.com, linux-kernel@vger.kernel.org, mark@fasheh.com, ocfs2-devel@lists.linux.dev, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 566771afc7a8 Merge tag 'v6.18-rc2-smb-server-fixes' of git.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=112ec7e2580000 kernel config: https://syzkaller.appspot.com/x/.config?x=25811b07889c90db dashboard link: https://syzkaller.appspot.com/bug?extid=fd8af97c7227fe605d95 compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=141ca614580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=156b4be2580000 Downloadable assets: disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-566771af.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/d8d15ef51fac/vmlinux-566771af.xz kernel image: https://storage.googleapis.com/syzbot-assets/7f77bbb0b916/bzImage-566771af.xz mounted in repro: https://storage.googleapis.com/syzbot-assets/34711c27aae5/mount_0.gz fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=1061bb04580000) IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+fd8af97c7227fe605d95@syzkaller.appspotmail.com option from the mount to silence this warning. ======================================================= ocfs2: Mounting device (7,0) on (node local, slot 0) with writeback data mode. Oops: divide error: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 5467 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:ocfs2_bg_discontig_add_extent fs/ocfs2/suballoc.c:335 [inline] RIP: 0010:ocfs2_block_group_fill+0x5bd/0xa70 fs/ocfs2/suballoc.c:386 Code: 34 1a 49 81 c6 50 01 00 00 45 0f b7 3f 49 83 c5 02 4c 89 e8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 eb 03 00 00 44 89 f8 31 d2 <66> 41 f7 75 00 0f b7 d8 4c 89 f0 48 c1 e8 03 42 0f b6 04 20 84 c0 RSP: 0018:ffffc90002b2f080 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888000dba480 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90002b2f188 R08: 00313050554f5247 R09: 00313050554f5247 R10: dffffc0000000000 R11: ffffed1009f9b801 R12: dffffc0000000000 R13: ffff88804fcc24c2 R14: ffff88804fcdc150 R15: 0000000000000000 FS: 000055558f3fe500(0000) GS:ffff88808d733000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2fd63fff CR3: 00000000431d7000 CR4: 0000000000352ef0 Call Trace: ocfs2_block_group_alloc_discontig fs/ocfs2/suballoc.c:634 [inline] ocfs2_block_group_alloc fs/ocfs2/suballoc.c:703 [inline] ocfs2_reserve_suballoc_bits+0x20a6/0x4640 fs/ocfs2/suballoc.c:834 ocfs2_reserve_new_inode+0x4f4/0xcc0 fs/ocfs2/suballoc.c:1074 ocfs2_mknod+0x83c/0x2050 fs/ocfs2/namei.c:306 ocfs2_mkdir+0x191/0x440 fs/ocfs2/namei.c:659 vfs_mkdir+0x306/0x510 fs/namei.c:4453 do_mkdirat+0x247/0x590 fs/namei.c:4486 __do_sys_mkdirat fs/namei.c:4503 [inline] __se_sys_mkdirat fs/namei.c:4501 [inline] __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4501 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3f05d8efc9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffdff269308 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007f3f05fe5fa0 RCX: 00007f3f05d8efc9 RDX: 0000000000000000 RSI: 00002000000000c0 RDI: ffffffffffffff9c RBP: 00007f3f05e11f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f3f05fe5fa0 R14: 00007f3f05fe5fa0 R15: 0000000000000003 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:ocfs2_bg_discontig_add_extent fs/ocfs2/suballoc.c:335 [inline] RIP: 0010:ocfs2_block_group_fill+0x5bd/0xa70 fs/ocfs2/suballoc.c:386 Code: 34 1a 49 81 c6 50 01 00 00 45 0f b7 3f 49 83 c5 02 4c 89 e8 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 eb 03 00 00 44 89 f8 31 d2 <66> 41 f7 75 00 0f b7 d8 4c 89 f0 48 c1 e8 03 42 0f b6 04 20 84 c0 RSP: 0018:ffffc90002b2f080 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888000dba480 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90002b2f188 R08: 00313050554f5247 R09: 00313050554f5247 R10: dffffc0000000000 R11: ffffed1009f9b801 R12: dffffc0000000000 R13: ffff88804fcc24c2 R14: ffff88804fcdc150 R15: 0000000000000000 FS: 000055558f3fe500(0000) GS:ffff88808d733000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2fd63fff CR3: 00000000431d7000 CR4: 0000000000352ef0 ---------------- Code disassembly (best guess): 0: 34 1a xor $0x1a,%al 2: 49 81 c6 50 01 00 00 add $0x150,%r14 9: 45 0f b7 3f movzwl (%r15),%r15d d: 49 83 c5 02 add $0x2,%r13 11: 4c 89 e8 mov %r13,%rax 14: 48 c1 e8 03 shr $0x3,%rax 18: 42 0f b6 04 20 movzbl (%rax,%r12,1),%eax 1d: 84 c0 test %al,%al 1f: 0f 85 eb 03 00 00 jne 0x410 25: 44 89 f8 mov %r15d,%eax 28: 31 d2 xor %edx,%edx * 2a: 66 41 f7 75 00 divw 0x0(%r13) <-- trapping instruction 2f: 0f b7 d8 movzwl %ax,%ebx 32: 4c 89 f0 mov %r14,%rax 35: 48 c1 e8 03 shr $0x3,%rax 39: 42 0f b6 04 20 movzbl (%rax,%r12,1),%eax 3e: 84 c0 test %al,%al --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.